Inhibition of Angiotensin I Converting Enzyme by Flavanolic Compounds: In Vitro and In Vivo Studies

Abstract

The procyanidolic oligomers coming from Vitis vinifera L. (two fractions) and Cupressus sempervirens L. (three fractions), and the monomers, (+)-catechin, (-)-epicatechin were tested for their effects on angiotensin I converting enzyme (ACE) activity. The oligomers are the most active (dose I₅₀ of 0.08 mg/ml for the fraction A of Vitis, the most active substance). Monomers have little activity. In vivo, the vasopressive response to Ang I is inhibited by approximately 20% to 40% in the rabbit after administration of procyanidolic oligomers (5 mg/kg i. v.). Ang II also is inhibited which suggests another action, perhaps due to the forming of compounds between Ang I and II and the oligomers.